Goldberg H, et al. – In this study, the performance of retrograde intrarenal surgery (RIRS) for the 1–2 cm renal stone size range in comparison to smaller stones was tested. In context of the findings, although the overall stone free rate following RIRS for renal stones up to 2 cm is generally high, the stone free rate for 15–20 mm stones is significantly lower, with a longer operating time and hospital stay, and a higher complication rate.